1. Field of the Invention
The present invention relates to an image forming apparatus such as a copier.
2. Description of the Prior Art
In the field of copiers there are already known those designed for simple real-size black-and-white copying, those capable of color copying, those capable of copying with modified image magnification, and those capable of copying with automatic successive feeding of originals. In general, however, such copiers are excessively large-sized and complicated to be acceptable to the ordinary users. Besides such copiers require complicated operations and are associated with a slow copying speed. Particularly those designed for making multiple copies from each of successively fed originals are associated with a complicated structure and a very low copying speed, and are therefore not suitable for achieving high-speed copying though they serve manpower saving. Also such copiers may result in jamming or originals under feeding, thus often leading to damage of valuable originals.
Besides in apparatus utilizing sheet detection by optical reflection for the purpose of jamming detection, it is difficult to achieve a satisfactory detection sensitivity, since the sheet to be detected can be rarely brought to the position of the maximum sensitivity of the detecting device. Such detecting device tends to cause detection errors particularly for the sheets transported in a slightly curved state, thus increasing the jamming and leading to fatal troubles such as original breakage.